Persistent Chlamydia Pneumoniae serology is related to decline in lung function in women but not in men. Effect of persistent Chlamydia pneumoniae infection on lung function

BACKGROUND Chlamydia pneumoniae (C pn) infection causes an acute inflammation in the respiratory system that may become persistent, but little is known about the long-term respiratory effects of C pn infections. AIM To estimate the long term respiratory effects of C pn with change in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) as a main outcome variable. METHODS The study comprised of 1109 subjects (500 men and 609 women, mean age 28 ± 6 years) that participated in the Reykjavik Heart Study of the Young. Spirometry and blood samples for measurements of IgG antibodies for C pn were done at inclusion and at the end of the follow-up period (mean follow-up time 27 ± 4 years). RESULTS Having IgG against C pn at both examinations was significantly associated to a larger decrease in FEV1 (6 mL/year) and FVC (7 mL/year) in women but not in men. In women the association between C pn and larger FEV1 decline was only found in women that smoked at baseline where having C pn IgG was associated with 10 mL/year decline compared to smokers without C pn IgG. These results were still significant after adjustment for age, smoking and change in body weight. CONCLUSION Our results indicate that persistent C pn serology is related to increased decline in lung function in women but not in men. This effect was, however, primarily found in smoking women. This study is a further indication that the pathophysiological process leading to lung impairment may differ between men and women.